CARDIFF, WALES - When your closest friend can turn into you bitterest rival in the time it takes to sign a contract, boxing is a solitary sport.

Just a few months ago, Sugar Ray Leonard was guest of honour at a post-fight press conference to celebrate Joe Calzaghe's win over Sakio Bika and the success of his HBO debut.

There appeared to be an immediate bond between the two, as they swapped stories in that way only those who have stepped between the ropes can.

As well as being mutual, their genuine respect was obvious.

Calzaghe was probably hoping to renew that relationship today at the Millennium Stadium Cardiff, when Leonard visited the Welsh capital to promote the Welshman's 20th title defence against Peter Manfredo Jnr.

But hopes of a cozy chat were dashed when Leonard announced that instead of just championing Manfredo's cause, he would be training him as well!

Reigning WBO/The Ring magazine super middleweight champion Calzaghe looked shocked, before dismissing the impact Leonard would have on Manfredo as neglible.

However it remains something of a coup for the American challenger, who had suffered a major blow in the build up to the fight when it was announced that Freddie Roach would abandon him for Oscar De La Hoya.

A former five-weight world champion, Leonard doesn't compare to Roach in terms of a second, but his mere status as one of the greats of the sport will put a spring in Manfredo's step.

It throws another piece of intrigue into the ahead of the April 7 show, which is already promising to be one of the biggest in British boxing history.

"I'm not a trainer, but my skill is in tactics and strategy," said Leonard, whose only previous cornering experience was for his brother.

Yet he has already worked closely with Manfredo on the hit reality TV series Contender, and believes he has what it takes to beat Calzaghe.

Following the announcement, Calzaghe was able to reign his surprise, and once again played down Manfredo's chances.

"I don't care who he has in his corner, he isn't going to beat me, it's as simple as that," said the undefeated 34-year-old.

There are those who would suggest that even with a combination of Eddie Futch, Angelo Dundee and Manny Steward, Manfredo doesn't stand a chance.

One who would agree is Calzaghe's trainer, his father Enzo, and he was equally unmoved by Leonard's decision.

"It could even do more harm than good," said Calzaghe snr.

"I don't think any trainer in the world is going to be able to change a fighter eight weeks before a fight.

"And asking someone to adapt to your way of doing things in short notice could create more problems than it solves."

Meanwhile the Millennium Stadium card is on course to go ahead in front of the biggest live gate an HBO broadcast has ever been associated with, and smash UK box office records.

"Every seat in the stadium, from the most expensive to the cheapest, has a fantastic view," added Sports Network's Ed Simons. "The fans will be in for a treat wherever they are watching."